Semiconductor memory device and method of fabricating the same

ABSTRACT

Provided is a semiconductor device and method of fabricating the semiconductor memory device. The semiconductor device may be formed by forming a first welding groove along outside edges of one case of a pair of upper and lower cases, forming a first welding protrusion along outside edges of the other case, the first welding protrusion being formed to correspond to the first welding groove and having a volume larger than a volume of the first welding groove. The method may further include inserting the first welding protrusion into the first welding groove to enclose a memory module in an inner accommodating space of the upper and lower cases, melting the first welding protrusion so that a first portion of the first welding protrusion fills the first welding groove and a second portion of the first welding protrusion fills a space between welding portions of the upper case and the lower case, and solidifying the first and second portions of the first welding protrusion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No. 12/659,150filed Feb. 26, 2010, which claims priority under 35 U.S.C. §119 toKorean Patent Application 10-2009-0019952, filed on Mar. 9, 2009, in theKorean Intellectual Property Office (KIPO), the entire contents of eachof which are herein incorporated by reference.

BACKGROUND

1. Field

Example embodiments of inventive concepts relate to a semiconductormemory device and a method of fabricating the same, and moreparticularly, to a memory card that may be used as a storage device inwhich a semiconductor device is provided and a method of fabricating thememory card.

2. Description of the Related Art

A memory card, for example, an SD card, is one of many memory devicesthat may store a relatively large amount of image information, speechinformation or other information in a semiconductor memory device (forexample, a flash memory). Because the memory card directly andelectrically accesses information to a nonvolatile memory formed in amemory device, it does not need a mechanical system unlike known storagedevices and therefore the writing and reading operations are relativelyfast. In addition, because the memory card is relatively small andlight, it has relatively good portability. Accordingly, the memory cardis primarily used as an auxiliary memory device in the digitalappliances, which need portability, for example, a personal computer, acellular phone, or a digital camera.

SUMMARY

Example embodiments of inventive concepts provide a semiconductor memorydevice, which may have improved mechanical strength and durability, anda method of fabricating the same.

In accordance with example embodiments of inventive concepts, a methodof fabricating a semiconductor memory device may include forming a firstwelding groove along outside edges of one case of a pair of upper andlower cases, forming a first welding protrusion along outside edges ofthe other case, the first welding protrusion being formed to correspondto the first welding groove and having a volume larger than a volume ofthe first welding groove. The method may further include inserting thefirst welding protrusion into the first welding groove to enclose amemory module in an inner accommodating space of the upper and lowercases, melting the first welding protrusion so that a first portion ofthe first welding protrusion fills the first welding groove and a secondportion of the first welding protrusion fills a space between weldingportions of the upper case and the lower case, and solidifying the firstand second portions of the first welding protrusion.

In accordance with example embodiments of inventive concepts, a methodof fabricating a semiconductor memory device may include welding a pairof upper and lower cases to each other to enclose a memory module in aninner accommodating space of the upper and lower cases, wherein weldingthe pair of upper and lower cases to each other includes inserting awelding protrusion formed on one of the cases of the pair of the upperand lower cases into a welding groove formed in the other of the pair ofthe upper and lower cases and melting the welding protrusion to fill thewelding groove.

In accordance with example embodiments of inventive concepts, a methodof fabricating a semiconductor memory device may include forming awelding groove along outside edges of any one of a pair of upper andlower cases, forming a welding protrusion along outside edges of theother case so as to have a volume larger than that of the welding grooveat a position facing the welding groove, melting the welding protrusionin a state where a leading end of the welding protrusion is insertedinto the welding groove so as to hold a memory module mountingsemiconductor devices in a space between the upper and lower cases,filling a melt of the welding protrusion in the welding groove andbetween welding surfaces on the edges of the upper and lower cases, andjoining the upper and lower cases by solidifying the melt of the weldingprotrusion.

In Example embodiments of inventive concepts, inner welding walls may beprotruded and formed at an inner side of the outside edges of the upperand lower cases so as to face each other and facing surfaces of theinner welding walls may be joined to each other by welding. In addition,the welding groove may be formed in any one of the facing surfaces ofthe inner welding walls, and the welding protrusion may be formed in theother facing surface, and the welding protrusion may have a largervolume than the welding groove.

In example embodiments of inventive concepts, the inner welding wallsmay be provided as a separation wall that partitions the inneraccommodating space into a holding space and a non-holding space of thememory module.

In example embodiments of inventive concepts, strength reinforcing ribsmay be protruded and formed at the upper and lower cases correspondingto the non-holding space of the memory module.

In example embodiments of inventive concepts, the ribs formed at theupper and lower cases may be protruded and formed to face each other,and facing surfaces of the ribs may be joined to each other by thewelding. Moreover, the welding groove may be formed in one of the facingsurfaces of the ribs, and the welding protrusion may be formed in theother facing surface, and the welding protrusion may have larger volumethan the welding groove.

In example embodiments of inventive concepts, the ribs may include aplurality of first ribs disposed so as to be horizontal in alongitudinal direction. In accordance with example embodiments ofinventive concepts, the plurality of first ribs may be spaced apart fromone another in parallel. In accordance with example embodiments ofinventive concepts a plurality of second ribs may be disposed so as tobe perpendicular to the first ribs and be spaced apart from one anotherin parallel.

In example embodiments of inventive concepts, the ribs may furtherinclude third ribs disposed so as to connect intersection points, whichare located at a diagonal direction, among intersection points betweenthe first ribs and the second ribs.

In example embodiments of inventive concepts, the ribs may include afirst rib disposed to be perpendicular to the inner welding wall andpartition a region of the upper and lower cases corresponding to thenon-holding space of the memory module, second ribs disposed adjacentlyat both sides of the first rib along a longitudinal direction and havinga diamond shape, third ribs connecting antipodes of the second ribs, andfourth ribs passing through contacts of the second ribs and disposed ina horizontal direction.

In example embodiments of inventive concepts, a metallic plate-shapedreinforcing member may be inserted into any one of the upper and lowercases corresponding to the non-holding space of the memory module, andthe ribs may penetrate the reinforcing member and may be spaced apartfrom one another in parallel.

Example embodiments of inventive concepts also provide a semiconductormemory device that may include a pair of upper and lower cases joined toeach other by a welding and a memory module held in an inneraccommodating space of the upper and lower cases to mount semiconductordevices. In example embodiments of inventive concepts, a welding groovemay be formed in any one welding surface of the upper and lower cases,and a junction portion welded between the upper and lower cases may befilled in the welding groove and between the welding surfaces of theupper and lower cases.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of example embodiments of inventive concepts, and areincorporated in and constitute a part of this specification. Thedrawings illustrate example embodiments of inventive concepts and,together with the description, serve to explain principles of theinventive concept. In the drawings:

FIG. 1 is a perspective view illustrating a semiconductor memory deviceaccording to example embodiments of inventive concepts;

FIG. 2 is an exploded perspective view illustrating the semiconductormemory device illustrated in FIG. 1;

FIG. 3 is a plan view illustrating upper and lower cases illustrated inFIG. 2;

FIG. 4A is a cross-sectional view of the upper case taken along theIVA-IVA′ line of FIG. 3;

FIG. 4B is a cross-sectional view of the lower case taken along theIVB-IVB′ line of FIG. 3;

FIGS. 5A and 5B are diagrams illustrating processes where the upper caseand the lower case are joined to each other by a welding;

FIG. 6 is an enlarged view of a portion “VI” of FIG. 5B;

FIGS. 7A and 7B are views illustrating a known welding structure;

FIGS. 8 through 10 are plan views illustrating upper and lower casesaccording to example embodiments of inventive concepts; and

FIG. 11 is an exploded perspective view of the lower case illustrated inFIG. 10.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF INVENTIVE CONCEPTS

Example embodiments of inventive concepts will now be described morefully with reference to the accompanying drawings, in which exampleembodiments of inventive concepts are shown. The invention may, however,be embodied in different forms and should not be construed as limited toof example embodiments of inventive concepts set forth herein. Rather,example embodiments of inventive concepts are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the invention to those skilled in the art. In the drawings, thesizes of components may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to”, or “coupled to” another element or layer, itcan be directly on, connected to, or coupled to the other element orlayer or intervening elements or layers that may be present. Incontrast, when an element is referred to as being “directly on”,“directly connected to”, or “directly coupled to” another element orlayer, there are no intervening elements or layers present. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer, and/orsection from another element, component, region, layer, and/or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of example embodiments ofinventive concepts.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Example embodiments of inventive concepts described herein will refer toplan views and/or cross-sectional views by way of ideal schematic views.Accordingly, the views may be modified depending on manufacturingtechnologies and/or tolerances. Therefore, example embodiments ofinventive concepts are not limited to those shown in the views, butinclude modifications in configuration formed on the basis ofmanufacturing processes. Therefore, regions exemplified in figures haveschematic properties and shapes of regions shown in figures exemplifyspecific shapes or regions of elements, and do not limit exampleembodiments of inventive concepts.

A semiconductor memory device and a method of fabricating thesemiconductor memory device according to example embodiments ofinventive concepts will be described below in more detail with referenceto the accompanying drawings. First, it is to be noted that the sameelements are indicated with the same reference numerals throughout thedrawings. For the purposes of clarity and simplicity, well-knownfunctions or constructions are not described in detail as they wouldobscure the invention in unnecessary detail.

FIG. 1 is a perspective view illustrating a semiconductor memory deviceaccording to example embodiments of inventive concepts, and FIG. 2 is anexploded perspective view illustrating the semiconductor memory deviceillustrated in FIG. 1.

Referring to FIGS. 1 and 2, the semiconductor memory device 1 accordingto example embodiments of inventive concepts may include a case 10 and amemory module 20. The case 10 may have an upper case 100 and a lowercase 200. The memory module 20 may be held in an inner accommodatingspace formed by a coupling of the upper case 100 and the lower case 200.In accordance with example embodiments of inventive concepts, thesemiconductor memory device 1 may be an SD card.

The upper case 100 and the lower case 200 may be formed of a plasticmaterial, for example, a polycarbonate resin and/or an ABS resin.Moreover, the upper case 100 and the lower case 200 may be joined toeach other by welding (or otherwise, melting and solidifying) theoutside edges. An example of the welding operation may include anultrasonic welding or a thermal welding.

The junction portion welded between the upper and lower cases 100 and200 may prevent or reduce external static electricity from entering intothe case 10 and may affect the mechanical strength, for example, abending strength or a torsional strength of the case 10.

The memory module 20 built in the case 10 may include a card substrate22 and a semiconductor device 24. The card substrate 22 may include aprinted circuit board (PCB) formed of a plastic material, for example, aglass-epoxy resin and/or BT resin. A wiring network may be formed in theinside or upper and lower surfaces of the card substrate 22. An externalconnection terminal (not illustrated) may be provided at one side on thelower surface of the card substrate 22 so as to be exposed through anopening 230 of the lower case 200. A semiconductor device 24, forexample, a flash memory or a controller, may be mounted on the uppersurface of the card substrate 22. The external connection terminal (notillustrated) and the semiconductor device 24 may be electricallyconnected to the wiring network of the card substrate 22.

A switch knob 30 may be provided in the side portion of the case 10. Theswitch knob 30 may be used for a write protect and/or release of thesemiconductor memory device 10. The position thereof may be adjusted ina sliding manner.

FIG. 3 is a plan view illustrating the upper case 100 and the lower case200 illustrated in FIG. 2. In addition, FIG. 4A is a cross-sectionalview of the upper case 100 taken along the IVA-IVA′ line of FIG. 3, andFIG. 4B is a cross-sectional view of the lower case 200 taken along theIVB-IVB′ line of FIG. 3.

Referring to FIG. 3, FIGS. 4A, and 4B, except for the opening 230, theplane structure of the upper case 100 is a minor image with respect tothat of the lower case 200. The upper case 100 includes a first body 110having an approximately thin-rectangular plate shape and a first weldingportion 120 formed so as to protrude along the outside edges of thefirst body 110. The first welding portion 120 may be successivelyprotruded along the outside edges of the first body 110 or protruded soas to be intermittent at corners of the outside edges. The width of thefirst welding portion 120 may be constant, or otherwise, may varydepending on intermittent positions.

A welding protrusion 124 may be protruded from a first welding surface122 directed in the protruding direction of the first welding portion120. The welding protrusion 124 may be a triangle in section shape, butis not limited to thereto, and it may be formed to have various shapes,for example, a quadrangle or a trapezoid shape.

The lower case 200 includes a second body 210 having a mirror imageshape with respect to the first body 110 of the upper case 100, and asecond welding portion 220 protruding along the outside edges of thesecond body 210. The second body 210 may have a thin plate shape, and anopening 230 may be formed on one side of the second body 210 so as toexpose an external connection terminal of the memory module 20 (notillustrated).

The second welding portion 220 may be successively protruded along theoutside edges of the second body 210 or protruded so as to beintermittent at corners of the outside edges. The width of the firstwelding portion 220 may be constant, or otherwise, may vary depending onintermittent positions.

A welding groove 224 may be formed in the second welding surface 222directed to the protruding direction of the second welding portion 220.The section of the welding groove 224 may be a triangle shapecorresponding to the welding protrusion 124 of the first welding portion120, but it is not limited to thereto, and it may be formed to have anyother section shapes different from the welding protrusion 124.

The welding protrusion 124 formed at the first welding portion 120 ofthe upper case 100 has larger volume than the welding groove 224 formedat the second welding portion 220 of the lower case 200. Because thewelding protrusion 124 has larger volume than the welding groove 224,the welding area is increased when the first welding portion 120 isjoined to the second welding portion 220 by the welding (melting andsolidifying). A detailed description thereof will be described belowwith reference to FIGS. 5 and 6.

FIG. 3 illustrates a case where the welding protrusion 124 is formed atthe first welding portion 120 of the upper case 100 and the weldinggroove 224 is formed at the second welding portion 220 of the lower case200. However, the welding protrusion 124 may be formed at the secondwelding portion 220 of the lower case 200, and the welding groove 224may be formed at the first welding portion 120 of the upper case 100.

FIGS. 5A and 5B are diagrams illustrating processes where the upper caseand the lower case are joined to each other by welding, and FIG. 6 is anenlarged view of a portion “VI” of FIG. 5B.

With respect to a process where the first welding portion 120 of theupper case 100 and the second welding portion 220 of the lower case 200are joined to each other by welding (melting and solidifying), it willbe described hereafter with reference to FIGS. 5A and 5B, and FIG. 6. Anexample of the welding may include ultrasonic welding using ultrasonicvibration energy.

The memory module (not illustrated) may be held in a space between theupper case 100 and the lower case 200, and the upper case 100 may belocated on the lower case 200 such that a leading end of the weldingprotrusion 124 is inserted into the welding groove 224. Under thisstate, the upper case 100 may be pressed and at the same time ultrasonicvibration energy may be applied (see FIG. 5A).

A contact portion between the welding protrusion 124 and the weldinggroove 224 may be vibrated by the ultrasonic vibration energy, and thewelding protrusion 124 may be molten by vibration friction. Because thewelding protrusion 124 has larger volume than the welding groove 224, aportion of the molten welding protrusion 124 may fill in the weldinggroove 224 and the rest may fill a region between the first weldingsurface 122 of the first welding portion 120 and the second weldingsurface 222 of the second welding portion 220, thereby forming ajunction portion (J). The junction portion (J) is solidified, and thefirst welding portion 120 of the upper case 100 and the second weldingportion 220 of the lower case 200 is joined to each other by thesolidified junction portion (J). In example embodiments of inventiveconcepts, the term “the molten welding protrusion 124” is also referredto as “a melt of a welding protrusion”.

The junction portion (J) comes in contact with the first welding surface122 of the first welding portion 120 and the second welding surface 222and the welding groove 224 of the second welding portion 220. A contactarea between the junction portion (J) and the second welding portion 220may be larger than the contact area between the junction portion (J) andthe first welding portion 120 due to the welding groove 224 (see FIGS.5B and 6).

In the related art, as illustrated in FIG. 7A, a welding protrusion 124′is formed on any one surface 122′ of welding surfaces 122′ and 222′, andthe other one surface 222′ has a plane shape. As illustrated in FIG. 7B,accordingly, the junction portion (J′) coming in contact with thewelding surface 122′ has the same contact area as the junction portion(J′) coming in contact with the welding surface 222′.

According to example embodiments of inventive concepts, however, thewelding groove 224 is formed in the second welding surface 222, and thewelding protrusion 124 formed in the first welding surface 122 has avolume larger than that of the welding groove 224. Accordingly, thewelding area where the junction portion (J) comes in contact with thesecond welding surface 222 is enlarged in comparison to the related art.

When the welding area is enlarged, the welding strength between thefirst welding portion 120 and the second welding portion 220 isincreased. Consequently, the mechanical strength, for example, a bendingstrength or a torsional strength, of the case 10, may be improved, thus,the durability of the case 10 may be improved.

Referring again to FIG. 3, the upper case 100 may have a first innerwelding wall 140, and the lower case 200 may have a second inner weldingwall 240. The first and second inner welding walls 140 and 240 may beprovided as a separation wall, which partitions an accommodating spaceinside the case 10 into one space 51 holding the memory module 20 andthe other space S2 not holding the memory module 20. Further, the innerwelding walls 140 and 240 may be provided as different shapes at theposition where the interior design of the upper and lower cases 100 and200 is not restricted.

The first inner welding wall 140 may be protruded from the first body110 of the upper case 100 so as to be horizontal in a longitudinaldirection. The second inner welding wall 240 may be protruded from thesecond body 210 of the lower case 200 so as to face the first innerwelding wall 140. The welding protrusion 142 may be formed on a surfaceof the first inner welding wall 140 facing the second inner welding wall240, and the welding groove 242 may be formed on a surface of the secondinner welding wall 240 facing the first inner welding wall 140. In thealternative, the welding groove may be formed at the first inner weldingwall 140, and the welding protrusion may be formed at the second innerwelding wall 240.

The first inner welding wall 140 and the second inner welding wall 240may be joined to each other by welding the facing surfaces. Because thewelding process is similar to the process described above with referenceto FIGS. 5A and 5B, and FIG. 6, the description thereof will be omittedfor the sake of brevity.

A strength reinforcing rib 150 may be provided in the upper case 100,and a strength reinforcing rib 250 may be provided in the lower case200. The ribs 150 and 250 may be formed in a region corresponding to thespace S2 in which the memory module 20 is not held.

The rib 150 provided in the upper case 100 may include first ribs 150 aand second ribs 150 b. The first ribs 150 a and the second ribs 150 bmay be protruded from the first body 110 of the upper case 100. Thefirst ribs 150 a may be disposed so as to be horizontal in alongitudinal direction and be spaced apart from one another in parallel.The second ribs 150 b may be disposed so as to be perpendicular to thefirst ribs 150 a and be spaced apart from one another in parallel.

The rib 250 provided in the lower case 200 may include first ribs 250 aand second ribs 250 b. The first ribs 250 a and the second ribs 250 bmay be protruded from the second body 210 of the lower case 200 so as toface the first ribs 150 a and the second ribs 150 b provided in theupper case 100.

The rib 150 provided in the upper case 100 may be joined to the rib 250provided in the lower case 200 by welding the facing surfaces. Weldingprotrusions 152 a and 152 b may be formed on a surface of the rib 150(150 a and 150 b) facing the rib 250 (250 a and 250 b), and weldinggrooves 252 a and 252 b may be formed on a surface of the rib 250 (250 aand 250 b) facing the rib 150 (150 a and 150 b). In the alternative, thewelding grooves may be formed in the rib 150 (150 a and 150 b), and thewelding protrusions may be formed in the rib 250 (250 a and 250 b). Thewelding process of the rib 150 and the rib 250 is similar to the processdescribed above with reference to FIGS. 5A and 5B, and FIG. 6.Therefore, the description thereof will be omitted for the sake ofbrevity.

FIG. 3 illustrates a case where the welding protrusion or the weldinggroove is formed in the ribs, but the welding protrusion or the weldinggroove may be formed in only a portion of the ribs.

As described above, according to example embodiments of inventiveconcepts, the welding area between the first welding portion 120 and thesecond welding portion 220 is enlarged and the mechanical strength, forexample, a bending strength or a torsional strength of the case 10, maybe improved by virtue of the junction of the inner welding walls 140 and240 and the junction of the strength reinforcing ribs 150 and 250 byusing the similar welding structure.

FIGS. 8 to 10 illustrate examples of upper cases and lower casesaccording to example embodiments of inventive concepts. The upper cases100′, 100″, 100′″ and the lower cases 200′, 200″, 200′″ illustrated inFIGS. 8 to 10 are similar to the upper case 100 and lower case 200illustrated in FIG. 3, except for the structure of the rib. Accordingly,only ribs having different structures will be described below.

As illustrated in FIG. 8, a rib 150′ may be provided in the upper case100′. The rib 150′ may include first ribs 150 a′, second ribs 150 b′,and third ribs 150 c′. The first ribs 150 a′, the second ribs 150 b′,and the third ribs 150 c′ are protruded from the first body 110′ of theupper case 100′. The first ribs 150 a′ may be disposed so as to behorizontal in a longitudinal direction and be spaced apart from oneanother in parallel. The second ribs 150 b′ may be disposed so as to beperpendicular to the first ribs 150 a′ and be spaced apart from oneanother in parallel. The third ribs 150 c′ may be disposed so as toconnect intersection points, which are located at a diagonal direction,among intersection points between the first ribs 150 a′ and the secondribs 150 b′.

A rib 250′ may be provided in the lower case 200′. The rib 250′ mayinclude first ribs 250 a′, second ribs 250 b′, and third ribs 250 c′.The first ribs 250 a′, the second ribs 250 b′, and the third ribs 250 c′may be protruded from the second body 210′ of the lower case 200′ so asto face the first ribs 150 a′, the second ribs 150 b′, and the thirdribs 150 c′ provided in the upper case 100′.

The rib 150′ provided in the upper case 100′ and the rib 250′ providedin the lower case 200′ may be joined to each other by welding the facingsurfaces. The reference numeral 120′ represents a first welding portion,and reference numeral 124′ represents a welding protrusion, referencenumeral 140′ represents a first inner welding wall, reference numeral142′ represents a welding protrusion, reference numeral 220′ representsa second welding portion, reference numeral 224′ represents a weldinggroove, reference numeral 230′ represents an opening, reference numeral240′ represents a second inner welding wall, and reference numeral 242′represents a welding groove, which are not described herein.

The rib 150′ provided in the upper case 100′ may be joined to the rib250′ provided in the lower case 200′ by welding the facing surfaces.Welding protrusions 152 a′, 152 b′, and 152 c′ may be formed on asurface of the rib 150′ (150 a′, 150 b′, and 150 c′) facing the rib 250′(250 a′, 250 b′, and 250 c′), and welding grooves 252 a′, 252 b′, and252 c′ may be formed on a surface of the rib 250′ (250 a′, 250 b′, and250 c′) facing the rib 150′ (150 a′, 150 b′, and 150 c′). In thealternative, the welding grooves may be formed in the rib 150′ (150 a′,150 b′, and 150 c′), and the welding protrusions may be formed in therib 250′ (250 a′, 250 b′, and 250 c′). The welding process of the rib150′ and the rib 250′ is similar to the process described above withreference to FIGS. 5A and 5B, and FIG. 6. Therefore, the descriptionthereof will be omitted for the sake of brevity.

As illustrated in FIG. 9, a rib 150″ may be provided in an upper case100″, The rib 150″ may include first to fourth ribs 150 a″, 150 b″, 150c″, and 150 d″. The first to fourth ribs 150 a″, 150 b″, 150 c″, and 150d″ may be protruded from a first body 110″ of the upper case 100″. Thefirst ribs 150 a″ may be arranged so as to be perpendicular to the firstinner welding wall 140″. The second ribs 150 b″ may adjacently bearranged on both sides of the first rib 150 a″ along their longitudinaldirections. The second ribs 150 b″ may have a diamond shape. The thirdribs 150 c″ may be arranged so as to connect antipodes of the secondribs 150 b″. The fourth ribs 150 d″ may pass through contacts of thesecond ribs 150 b″ and may be arranged in a horizontal direction.

A rib 250″ may be provided in a lower case 200″. The rib 250″ mayinclude first to fourth ribs 250 a″, 250 b″, 250 c″, and 250 d″. Thefirst to fourth ribs 250 a″, 250 b″, 250 c″, and 250 d″ may be protrudedfrom a second body 210″ provided in the lower case 200″ so as to facethe first to fourth ribs 150 a″, 150 b″, 150 c″, and 150 d″.

The rib 150″ provided in the upper case 100″ and the rib 250″ providedin the lower case 200″ may be joined to each other by welding the facingsurfaces. The reference numeral 120″ represents a first welding portion,and reference numeral 124″ represents a welding protrusion, referencenumeral 142″ represents a welding protrusion, reference numeral 220″represents a second welding portion, reference numeral 224″ represents awelding groove, reference numeral 230″ represents an opening, referencenumeral 240″ represents a second inner welding wall, and referencenumeral 242″ represents a welding groove, which are not describedherein.

The rib 150″ provided in the upper case 100″ may be joined to the rib250″ provided in the lower case 200″ by welding the facing surfaces.Welding protrusions 152 a″, 152 b″, 152 c″, and 152 d″ may be formed ona surface of the rib 150″ (152 a″, 152 b″, 152 c″, and 15 d″) facing therib 250″ (250 a″, 250 b″, 250 c″, and 250 d″), and welding grooves 252a″, 252 b″, 252 c″, and 252 d″ may be formed on a surface of the rib250″ (250 a″, 250 b″, 250 c″, and 250 d″) facing the rib 150″ (150 a″,150 b″, 150 c″, and 150 d″). In the alternative, the welding grooves maybe formed in the rib 150″ (150 a″, 150 b″, 150 c″, and 150 d″), and thewelding protrusions may be formed in the rib 250″ (250 a″, 250 b″, 250c″, and 250 d″). The welding process of the rib 150″ and the rib 250″ issimilar to the process described above with reference to FIGS. 5A and5B, and FIG. 6. Therefore, the description thereof will be omitted forthe sake of brevity.

As illustrated in FIG. 10, a rib 150′″ provided in an upper case 100′″may be protruded from a first body 110′″ of the upper case 100′″. Aplurality of ribs 150′″ may be disposed so as to be perpendicular to afirst inner welding wall 140′″ in a longitudinal direction and be spacedapart from one another in parallel. A rib 250′″ may be provided in alower case 200′″ and may be protruded from a second body 210′″ of thelower case 200′″ so as to face the rib 150′″ provided in the upper case100′″. The rib 150′″ provided in the upper case 100′″ and the rib 250′″provided in the lower case 200′″ may be joined to each other by weldingthe facing surfaces.

The rib 150′″ provided in the upper case 100′″ may be joined to the rib250′″ provided in the lower case 200′″ by welding the facing surfaces.Welding protrusions 152′″ may be formed on a surface of the rib 150′″facing the rib 250′″, and welding grooves 252′″ may be formed on asurface of the rib 250′″ facing the rib 150′″. In the alternative, thewelding grooves may be formed in the rib 150′″, and the weldingprotrusions may be formed in the rib 250′″. The welding process of therib 150′″ and the rib 250′″ is similar to the process described abovewith reference to FIGS. 5A and 5B, and FIG. 6. Therefore, thedescription thereof will be omitted for the sake of brevity.

In addition to the rib 250′″, a strength reinforcing member 260 may beprovided in the lower case 200′″. The reinforcing member 260 may be ametallic plate. In the reinforcing member 260, as illustrated in FIG.11, holes 262 may be formed so as to be penetrated by the ribs 250′″,and holes 264 may be formed so as to be penetrated by pins 254 forfixing the reinforcing member 260. The reinforcing member 260 may beconfigured to come in contact with the second body 210′″ of the lowercase 200′″ in a state where the ribs 250′″ and the pins 254 are insertedinto the holes 262 and 264. The reinforcing member 260 may be providedin the upper case 100′″ with the same configuration as provided in thelower case 200′″.

The reference numeral 120′″ represents a first welding portion,reference numeral 124′″ represents a welding protrusion, referencenumeral 142′″ represents a welding protrusion, reference numeral 220′″represents a second welding portion, reference numeral 224′″ representsa welding groove, reference numeral 230′″ represents an opening,reference numeral 240′″ represents a second inner welding wall, andreference numeral 242′″ represents a welding groove, which are notdescribed herein.

The above-described example embodiments of the inventive conceptsdescribe the SD card as a semiconductor memory device, but are notlimited thereto. The inventive concept may be applicable to varioussemiconductor memory devices capable of accommodating the substrate onwhich semiconductor devices are mounted in a pair of cases.

According to example embodiments of inventive concepts, the weldingstrength may be improved by enlarging the welding area of the weldingportion of the case in the semiconductor memory device.

In addition, according to example embodiments of inventive concepts, itcan improve the mechanical strength and durability of the case in thesemiconductor memory device.

The above-disclosed subject matter is to be considered illustrative andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope of the inventive concept. Thus, to the maximumextent allowed by law, the scope of the inventive concept is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

What is claimed is:
 1. A case for holding a memory device comprising: afirst cover including a first upper portion, a first lower portion andan inner wall separating the first upper portion and the first lowerportion, the first lower portion including a plurality of ribs on aninner surface of the first cover; and a second cover including a secondupper portion and a second lower portion, wherein the first upperportion and the second upper portion are configured to hold the memorydevice in an inner accommodating room formed by coupling the first coverand the second cover, each of the first upper portion and the secondupper portion includes a first recessed portion at a first side edge, acontour of the first recessed portion of the first upper portion havinga mirror image to that of the first recessed portion of the second upperportion such that the first recessed portion of the first upper portionand the first recessed portion of the second upper portion are coupledto each other, the first recessed portion of the first upper portionbeing not extended to the first lower portion, the first recessedportion of the second upper portion being not extended to the secondlower portion, the first cover includes a plurality of openings in thefirst upper portion, the plurality of openings including a firstopening, a second opening and a third opening, sizes of the first tothird openings being different to one another in a width direction, thesecond and the third openings aligned in a row, while the first openingbeing off-axis from a center of the row in an arrangement direction, thecase is configured to accommodate only one memory device, a bottom edgeof the first cover at the first lower portion has a substantiallystraight-line shape and runs substantially parallel with the first innerwall, and the plurality of ribs include a plurality of first-type ribs,the plurality of first-type ribs being perpendicular to the inner wallof the first cover, the plurality of first-type ribs being arranged suchthat a first distance between an outermost one of the plurality offirst-type ribs and an adjacent side edge of the first cover is shorterthan a second distance between two neighboring ones of the plurality offirst-type ribs.
 2. The case of claim 1, wherein the plurality offirst-type ribs are arranged at equidistant intervals.
 3. The case ofclaim 1, wherein each of the first upper portion and the second upperportion includes a second recessed portion at a second side edgethereof, the second recessed portion of the first upper portion having amirror image to the second recessed portion of the second upper portionsuch that the second recessed portion of the first upper portion and thesecond recessed portion of the second upper portion are coupled to eachother, the second recessed portion of the first upper portion being notextended to the first lower portion, the second recessed portion of thesecond upper portion being not extended to the second lower portion, asize of the first recessed portion being different from a size of thesecond recessed portion.
 4. The case of claim 1, wherein each of thefirst cover and the second cover includes at least one welding portionalong a contour thereof.
 5. The case of claim 1 further comprising: aninsertable reinforcing member coupled to one of the first lower portionand the second lower portion, a depth of a space defined by one of thefirst lower portion and the second lower portion, which is coupled withthe insertable reinforcing member, being greater than a depth of a spacedefined by the other of the first upper portion and the second upperportion.
 6. The case of claim 1, wherein at least some of the pluralityof first-type ribs connect the inner wall of the first cover to thebottom edge of the first cover.
 7. The case of claim 1, wherein theplurality of first-type ribs are spaced apart from both the inner wallof the first cover and the bottom edge of the first cover.
 8. The caseof claim 1, wherein the memory device is connected to terminals of anexternal device through the plurality of openings.
 9. The case of claim1, wherein each of the first cover and the second cover has a chamferedcorner.
 10. A case for holding a memory device comprising: a first coverincluding a first upper portion, a first lower portion and a first innerwall separating the first upper portion and the first lower portion, thefirst lower portion including a plurality of ribs on an inner surface ofthe first cover; and a second cover including a second upper portion anda second lower portion, wherein the first upper portion and the secondupper portion are configured to hold the memory device in an inneraccommodating room formed by coupling the first cover and the secondcover, each of the first upper portion and the second upper portionincludes a first recessed portion at a first side edge, a contour of thefirst recessed portion of the first upper portion having a mirror imageto that of the first recessed portion of the second upper portion suchthat the first recessed portion of the first upper portion and the firstrecessed portion of the second upper portion are coupled to each other,the first recessed portion of the first upper portion being not extendedto the first lower portion, the first recessed portion of the secondupper portion being not extended to the second lower portion, at leastone of the first cover and the second cover includes a plurality ofopenings in at least one corresponding upper portion from among thefirst upper portion and in the second upper portion, the plurality ofopenings including a first opening, a second opening, and a thirdopening, sizes of the first to third openings being different to oneanother in a width direction, the second and the third openings alignedin a row, while the first opening arranged off-axis from a center of therow in an arrangement direction, the case is configured to accommodateonly one memory device, and the plurality of ribs include a plurality offirst-type ribs, the plurality of first-type ribs being perpendicular tothe inner wall of the first cover, the plurality of first-type ribs arearranged such that distances between two adjacent ones of the pluralityof first-type ribs are substantially equal, and the plurality offirst-type ribs are separate from a bottom edge of the first cover, thebottom edge of the first cover at the first lower portion runningsubstantially parallel with the inner wall, wherein the plurality offirst-type ribs are arranged such that a distance between an outermostone of the plurality of first-type ribs and an adjacent side edge of thefirst cover, the adjacent side edge running parallel with the pluralityof first-type ribs, is shorter than a distance between the two adjacentones of the plurality of first-type ribs.
 11. The case of claim 10,wherein the plurality of first-type ribs include a first rib and asecond rib, a length of the first rib being substantially equal to alength of the second rib.
 12. The case of claim 10, wherein some or anentirety of the plurality of first-type ribs connect the inner wall ofthe first cover to the bottom edge of the first cover.
 13. The case ofclaim 10, wherein the plurality of first-type ribs are spaced apart fromboth the inner wall of the first cover and the bottom edge of the firstcover.
 14. The case of claim 10, wherein the memory device is connectedto terminals of an external device through the plurality of openings.15. The case of claim 10, wherein each of the first cover and the secondcover has a chamfered corner.
 16. The case of claim 10, wherein each ofthe first upper portion and the second upper portion includes a secondrecessed portion at a second side edge, a contour of the second recessedportion of the first upper portion having a mirror image to that of thesecond recessed portion of the second upper portion such that the secondrecessed portion of the first upper portion and the second recessedportion of the second upper portion are coupled to each other, thesecond recessed portion of the first upper portion being not extended tothe first lower portion, the second recessed portion of the second upperportion being not extended to the second lower portion, a size of thefirst recessed portion being different from a size of the secondrecessed portion.
 17. A semiconductor memory assembly comprising: afirst cover including a first upper portion, a first lower portion andan inner wall separating the first upper portion and the first lowerportion, the first lower portion including a plurality of ribs on aninner surface of the first cover; a second cover including a secondupper portion and a second lower portion; and a memory module includinga substrate and a semiconductor memory device mounted on the substrate,wherein a contour of the first cover has a mirror image to a contour ofthe second cover such that the first cover and the second cover arecoupled to each other to form a case for holding the memory device, thefirst upper portion and the second upper portion defines anaccommodating room to hold the memory device therein by the coupling ofthe first cover to the second cover, each of the first upper portion andthe second upper portion includes a first recessed portion at a firstside edge and a second recessed portion at a second side edge, a contourof the first recessed portion of the first upper portion having a mirrorimage to that of the first recessed portion of the second upper portionsuch that the first recessed portion of the first upper portion and thefirst recessed portion of the second upper portion are coupled to eachother, the first recessed portion of the first upper portion being notextended to the first lower portion, the first recessed portion of thesecond upper portion being not extended to the second lower portion, acontour of the second recessed portion of the first upper portion havinga mirror image to that of the second recessed portion of the secondupper portion such that the second recessed portion of the first upperportion and the second recessed portion of the second upper portion arecoupled to each other, the second recessed portion of the first upperportion being not extended to the first lower portion, the secondrecessed portion of the second upper portion being not extended to thesecond lower portion, a size of the first recessed portion beingdifferent from a size of the second recessed portion, at least one ofthe first cover and the second cover includes a plurality of openings inat least one corresponding upper portion from among the first upperportion and the second upper portion, the plurality of openingsincluding a first opening, a second opening, and a third opening, sizesof the first to third openings being different to one another in a widthdirection, the second and the third openings aligned in a row, while thefirst opening arranged off-axis from a center of the second opening andthe third opening in an arrangement direction, the accommodating room isconfigured to accommodate only one memory module, the plurality of ribsinclude a plurality of first-type ribs, the plurality of first-type ribsbeing substantially perpendicular to the inner wall of the first coverand being connected to the inner wall of the first cover, wherein theplurality of first-type ribs are arranged such that a distance betweenan outermost one of the plurality of first-type ribs and an adjacentside edge of the first cover, the adjacent side edge running in parallelwith the plurality of first-type ribs, is shorter than a distancebetween two adjacent ones among the plurality of first-type ribs. 18.The semiconductor memory assembly of claim 17, wherein the plurality offirst-type ribs are arranged at equidistant intervals.